1. Technical Field
The present disclosure relates to a quantum interference device, an atomic oscillator, an electronic device, and a moving object.
2. Related Art
As an oscillator, an atomic oscillator oscillates based on the transition of atomic energy of an alkali metal such as rubidium or cesium. The atomic oscillator may have highly accurate oscillation properties in the long term.
Generally, the operational principle of the atomic oscillator may be classified as a method using double resonance phenomena due to light beams and microwaves. The atomic oscillator may also be classified as a method using quantum interference effects (coherent population trapping (CPT)) due to two types of light beams having different wavelengths. In the methods, it is possible to miniaturize the atomic oscillator using the quantum interference effects rather than the atomic oscillator using the double resonance phenomena. Accordingly, an atomic oscillator can be mounted on various devices.
For example, JP-A-2014-17824 discloses an atomic oscillator using the quantum interference effects and includes, for example, a gas cell filled with gaseous alkali metal, a light source that resonates the alkali metal of the gas cell and emits a resonance light beam pair of two types of resonance light beams having different frequencies, and a light detector (reception device) that detects the resonance light beam pair that passes through the gas cell. In the atomic oscillator, an electromagnetically induced transparency (EIT) phenomenon, in which two types of resonance light beams pass through the gas cell without being absorbed into the alkali metal of the gas cell, occurs when the frequency difference of the two types of resonance light beams is a prescribed value. Further, in such an atomic oscillator, the light detector detects an EIT signal, which is a sharp signal generated in accordance with the EIT phenomenon, and uses the EIT signal as a reference signal.
From the point of view of increasing short-period frequency stability, it is preferable that the EIT signal has a small line width (half-value width) and high intensity. For example, in the atomic oscillator disclosed in JP-A-2014-17824, circularly polarized resonance light beam pairs are used in order to improve the intensity of the EIT signal.
However, the atomic oscillator disclosed in JP-A-2014-17824 has a problem in that the effect thereof is not sufficient.